In recent years, the technique using an organic semiconductor device has been attracting attention and, particularly, an organic EL display using an organic electroluminescent (hereinafter referred to as “organic EL” in some cases) device which is one embodiment of the organic semiconductor device has been attracting attention. An organic EL device used in the organic EL display is constituted by including an anode, a cathode, and a light emitting layer which is arranged between the anode and the cathode, and holes and electrons which are injected from the anode and the cathode, respectively, are bound in the light emitting layer, thereby, to emit light.
The organic EL device has an advantage that it is simply produced, and can form an organic layer such as a light emitting layer by a method which is easy in scaling the area up. Specifically, a liquid composition in which a material contained in an organic layer is dissolved or dispersed in an organic solvent is applied to a substrate in which an anode has been formed on a surface by an applying method such as a spin coating method or an inkjet method, and an applied film of the liquid composition is dried to form an organic layer such as a hole injecting layer or a light emitting layer. Thereafter, a cathode layer is formed on the organic layer, thereby, the organic EL device is manufactured.
As a liquid composition for an organic semiconductor device, for example, an applying solution containing a light emitting compound constituting a light emitting layer of an organic EL device, and a mixed solvent containing an aromatic compound is described in patent document 1. This applying solution uses both of a low boiling point aromatic compound and a high boiling point aromatic compound as a solvent. Thereby, this applying solution is controlled to have a relatively low viscosity although it has a relatively high boiling point, and the coating property has been improved.